Page 110 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Huff-n-puff injection in shale gas condensate reservoirs 97

Figure 4.19 Recovery factors of total hydrocarbons except methane from methane,
ethane, and methanol.

Sharma and Sheng (2017) also compared the performances of gases
(methane and ethane) and solvents (methanol and isopropyl alcohol
(commonly called isopropanol)) to recover Fluid B. Fluid B is composed
of 0.81 mol fraction C 1 , 0.05 C 4 , 0.06 C 7 , and 0.08 C 10 , richer than Fluid
A. There is 25% initial water saturation in the experiment. The experimental

temperature is 300 F. Overall, the isopropanol (IPA) performance is similar
to the methanol performance, with the former a little bit better than the
latter with higher cost. As IPA is heavy than methanol, IPA outperforms
methanol to recover heavy condensates. The ranking of these four gases
and solvents from high to low recovery factors is ethane, methane, IPA,
and methanol.
Generally, it is easier for gases to penetrate the liquid condensate, and
liquid solvents are more likely to solubilize the condensate. Since ethane
mixes with the condensate, it is difficult to split the produced condensate
and ethane in laboratory experiments. Simulation work proves that ethane
is the best injection fluid in recovering the total hydrocarbon in place.
It revaporizes condensate and reduces the dew point pressure of initial
reservoir fluid. Its supercritical fluid properties enable it to recover high
volumes of the total hydrocarbon fluid in place for relatively small volumes
of injection.